So much information. How wonderful that so many are willing to share. I am two years post DX, one year post treatment. Just wanted to say you are "normal" in your reaction. Be gentle on yourself, there is no right or wrong way to approach the changes that are happening in your life. Allow yourself time to adjust, time to be the strong one and when you need to give yourself permission to let go and have a good cry. Some ladies I know didnt do this until they returned to work or finished their last treatment. Holding strong enabled them to endure everything. Others let it all hang out. If you think you need help then ask - your medical team is expecting you too.
For your mouth try pawpaw (red is best), fruit tingle lollies (bicarb bombs) also soda water with lemon or lime (again it is bicarb).
Hugs from afar. Take care.